In order to reduce the number of road traffic accidents driver assistance systems are being used more and more. The currently integrated ACC (Adaptive Cruise Control) systems are comfort systems for automatic speed control which regulate speed depending on the distance and relative speed between one's own vehicle and the one in front. For future vehicles radar devices for drive assistance systems will no longer be categorised by vehicle manufacturers as comfort systems, but as systems that are critical to safety in order e.g. for the braking assistant to be able to execute full braking in order to avoid a collision because the driver has not applied the brake pedal or has done so too late. For this purpose the radar devices for driver assistance systems currently fitted in series-production vehicles have a functional disadvantage however. Independently of the object, a signal corresponding to the radar backscatter cross-section is received without one being able to draw any conclusion regarding the physical dimensions and the type of the object. The value of the radar backscatter cross-section does not allow one to draw any conclusion regarding the type and target size either because this value is greatly dependent upon the viewing angle. The reliable classification of objects according to the categories lorry, car, motorbike/bicycle, pedestrian or false targets (manhole cover, bridge parapet etc.) for activation of the braking assistant is therefore unresolved. Another challenge is the functional improvement of current systems with regard to fading (multiple reflections and the resulting ghost targets) and the effect of spray caused by vehicles driving ahead or that are overtaking.
The previous radar devices for drive assistance systems use linearly polarised waves.